Scope In CSS With and Without JavaScript

CSS is global by nature. Given the name, style sheets are intended to cascade and a single CSS rule could apply to multiple elements on your site. This is a powerful feature of CSS that can allow you to create consistent styling throughout your site with small amounts of code. But increasingly there are cases where front end developers want to instead scope their styles to a specific component and ensure that component styles are consistent and don’t impact other areas of the site.

This session will provide an overview of the various approaches to scoping CSS, both when using CSS alone, and when using CSS combined with JavaScript.

Starting from the perspective of CSS only approaches we’ll look at:

• A brief review of CSS Inheritance and the Cascade
• Scoping with BEM and other naming methodologies
• Atomic or Functional CSS

Next we’ll examine the various scoping approaches when using CSS in JavaScript, including:

• Scoped styles using CSS Modules
• React CSS in JS libraries including Styled Components and Emotion
• Component styling in Angular and Vue

Finally, we’ll wrap up by looking at a few ways that global and scoped CSS can be used together effectively.

• Approaches to using both global and scoped CSS when using CSS in JavaScript.
• Ways to share styles between ’traditional’ styling and CSS in JS approaches.